Acta Academiae Medicinae Sinica

Abstract: ABSTRACT:Objective To investigate the delayed cardioprotection induced by remifentanil in intact rat ischemia-reperfusion (I/R) models. Methods Totally 42 adult male Wistar rats weighing 200-300 g were randomly divided into 7 groups (n=6 in each group)：In Group Ⅰ, rats were injected with normal saline via tail vein，performed with the regimen of 3×5-min intravenous (IV) infusion at a rate of 0.1 ml&#8226;kg-1&#8226;min-1 24 h before I/R；In Group Ⅱ, rats were treated according to the same experimental protocols as in GroupⅠ except receiving additional naloxone (0.1 mg/kg) 10 minutes before normal saline pretreatment; In Groups Ⅲ, Ⅳ, Ⅴ, and Ⅵ, rats were treated with remifentanil via tail vein，performed with the regime of 3×5-min IV infusion at a rate of 2 μg&#8226;kg-1&#8226;min-1 12 h, 24 h, 48 h, and 72 h before I/R; In Group Ⅶ, the rats were treated according to the same experimental protocols as in Group Ⅳ except that they received additional naloxone (0.1 mg/kg) 10 minutes before remifentanil pretreatment. Heart rate（HR），mean arterial pressure (MAP), and a lead Ⅱ electrocardiogram were continuously monitored during IR process. To determine plasma concentration of creatine kinase myocardial isoenzyme-MB (CK-MB), arterial blood samples were obtained immediately before ischemia，and at the end of ischemia and reperfusion. After a 120-min reperfusion, heart was removed for the measurement of myocardial infarct size. Infarct size（IS） was expressed as percentage of the area at risk. Results HR, MAP, and rate-pressure product were not significantly different at each time points among all groups (P>0.05). Compared with Group Ⅰ, plasma concentrations of CK-MB at the end of ischemia and reperfusion and myocardial infarct size were significantly lower in Groups Ⅳ and Ⅴ (P<0.05). Compared with Group Ⅳ, plasma concentrations of CK-MB at the end of ischemia and reperfusion were significantly higher and myocardial infarct size was significantly larger in Group Ⅶ (P<0.05). Conclusion Remifentanil preconditioning induces delayed cardioprotection in intact rat ischemia-reperfusion model, which may be triggered via opioid receptors.

Key words: remifentanil, preconditioninc, iscdemia-reperfusion injury